1. Field of the Invention
The present invention relates to an apparatus and method for processing a slider, a load applying apparatus for processing a slider and an auxiliary device for processing a slider which are employed for chamfering edges of a slider used for a flying type magnetic head or the like.
2. Description of the Related Art
In general, a flying type magnetic head used in a magnetic disc drive or the like has a configuration in which a thin film magnetic head element is formed at the rear end of a slider. A slider generally has rail portions whose surfaces face a recording medium (air bearing surfaces) and has a taper or step portion in the vicinity of the end at the air inflow side such that the rail portions fly slightly above the surface of a recording medium such as a magnetic disc or the like because of a stream of air flowing in through the taper or step portion.
For example, as disclosed in Japanese unexamined patent publication (KOKAI) No. H6-282831, in order to prevent edges of a slider such as edges defined by the surfaces of the rail portions to face a recording medium and outer lateral walls of the rail portions from damaging the recording medium when the slider is inclined because of a shake or the like, a chamfering process is performed on the edges of the slider.
For example, as in Japanese unexamined patent publication (KOKAI) No. H6-12645, a method for chamfering on edges of a slider according to the related art is to put the surface of a slider to face a recording medium into contact with a diamond lapping sheet provided on an elastic element with a load applied thereto and to lap the slider by moving it relative to the diamond lapping sheet.
According to the above-described method for chamfering, a slider must be urged against the diamond lapping sheet by applying a load thereto. However, a problem has arisen in that the diamond lapping sheet can be cut by edges of a slider especially before the chamfering of the edges of the rail portions or at an early stage of the chamfering because the base material of the diamond lapping sheet is thin.
According to the above-described method for chamfering, it is further necessary during actual processing to urge a slider against the diamond lapping sheet by applying a load to a jig. On the contrary, the load must not be applied to the jig when the slider is attached to or removed from the processing apparatus. This necessitates a mechanism for applying the load to the jig only when needed.
A possible mechanism for this purpose is a mechanism having a weight with a shaft portion which can be put into contact with a jig at the lower end thereof and a large diameter portion greater in the diameter than the shaft portion and having a weight holding portion formed with a hole which allows the shaft portion of the weight to pass therethrough and which disallows the large-diameter portion to pass therethrough, for holding the weight movably in the axial direction of the shaft portion of the weight with the hole, the mechanism allowing the weight holding portion to be moved up and down.
However, such a mechanism has a problem in that the weight can not be smoothly moved relative to the weight holding portion because the shaft portion of the weight frequently rubs against the hole of the weight holding portion to generate chips (particles).
According to the above-described method for chamfering, the entire edges of a slider are substantially uniformly chamfered.
However, the above-described method for chamfering had a problem in that it does not allow a part of the edges of a slider, e.g., a region of the edges at the air inflow side of the slider, to be chamfered in a greater amount than in other regions of the edges even when it is desired.
A slider for a magnetic head is formed by cutting a wafer having a multiplicity of magnetic head elements formed in a matrix configuration in one direction to form blocks referred to as "bars" which include a plurality of magnetic head elements arranged in a row, forming rail portions on the bars and thereafter cutting the bars into each separate slider. Referring now to a slider as disclosed in Japanese unexamined patent publication (KOKAI) No. H6-282831, outer lateral walls of two rail portions serve as lateral walls of a slider as they are. However, the configuration as disclosed in Japanese patent publication (KOKAI) No. H6-282831 has a problem in that rail portions can be broken off (chipping) as a result of mechanical processing to cut bars into sliders.
For this reason, sliders as shown in FIG. 47 have become popular in which rail portions 213 are formed such that lateral walls 214 of the rail portions 213 are located inside lateral walls 212 of a slider 211 or cut portions of a bar with a predetermined distance therebetween. A slider having such a configuration will be hereinafter referred to as "a slider having a two-step structure".
In such a slider having a two-step structure, chamfering is also performed on edges of the rail portions. For example, as disclosed in Japanese unexamined patent publication No. H6-12645, a method for chamfering edges of rail portions according to the related art is to slide the slider on a diamond lapping sheet provided on an elastic element. FIG. 48 schematically illustrates the method for chamfering according to the related art. According to the method for chamfering of the related art, a plurality of sliders 211 are fixed to a jig 215 and are slid in two horizontal directions on a diamond lapping sheet 217 provided on a plate-like elastic member 216 formed from, for example, silicone rubber while urging them in the direction of the arrow indicated by a reference number 218 in the figure, thereby chamfering edges 219 of rail portions 213.
FIG. 49 is an enlarged view of the neighborhood of edges 219 of rail portions 213 (the region C in FIG. 48) which have been chamfered according to the method illustrated in FIG. 48.
As disclosed in Japanese unexamined patent publication (KOKAI) No. H2-301014, another method for chamfering according to the related art is to a lapping tape is moved back and forth under the guidance of a guide to thereby slide the lapping tape relative to rail portions of a slider.
There is a recent need for a reduction in the flying amount of a slider in order to improve the recording density. There is also a need for improved stability of the flying of a slider in order to increase access speed. Negative pressure sliders have recently come into use to satisfy such needs. In general, a negative pressure slider is formed with a projection for generating a negative pressure between the two rail portions thereof. In such a negative pressure slider, the surface toward a recording medium has a microscopic configuration and, especially, the height of the rail portions is significantly smaller than that in conventional sliders.
In such a negative pressure slider, as shown in FIG. 50, the small height of the rail portions has resulted in a problem in that a recording medium 225 can be put into contact with and damaged by an edge 224 defined by a lateral wall 222 of a slider 221 and a surface 223 of the slider toward the recording medium perpendicular thereto when the slider 221 is inclined. The above-described problem is significant especially in a hard disc device used in a portable apparatus such as a notebook type personal computer in which the slider is often inclined.
Under such circumstances, the inventors have proposed, for example in Japanese unexamined patent publication (KOKAI) No. H11-238214 and U.S. patent application Ser. No. 09/064,734, a technique for lapping and chamfering a plurality of edges having steps of a slider simultaneously by transforming a diamond lapping sheet using a wire. In this case, since processing accuracy is reduced if the tension of the wire is unstable, the tension of the wire must be made stable in order to improve processing accuracy.